Air circulator

ABSTRACT

An air circulator includes a blower unit that is provided with an airflow opening on its front side, and a support unit that supports the blower unit. A grill is provided in the airflow opening. The grill is provided with plural airflow guide blades in a spiral manner. Inner end portions thereof closer to the center of the spiral of the airflow guide blades are protruded from outer end portions thereof in an airflow direction. The blower unit has a cover for forming an outer panel thereof, and the cover has a spherical shape.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 16/646,983, which is the national phase of the PCT applicationNo. PCT/JP2018/035578 (Publication No. WO2019/065685) filed on Sep. 26,2018, which is based upon and claims the benefit of priority from theprior Japanese Patent Application No. 2017-191401 (filing date: Sep. 29,2017) and the prior Japanese Patent Application No. 2018-026445 (filingdate: Feb. 16, 2018), and the entire contents of them are incorporatedherein by reference.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to an air circulator.

Background Arts

Heretofore, an air circulator having a grill provided with spiral fins(airflow guide blades) have been proposed (for example, see JapanesePatent Application Publication No. 2010-54084). By agitating air in aroom by an air circulator to homogenize a temperature in the room, itbecomes possible to improve cooling efficiency of an air-conditioner onsummer season and thereby an energy-saving effect is expected, forexample.

SUMMARY OF THE INVENTION

In a prior-art air circulator, its grill provided in its airflow openinghas a flat planar structure, so that there is a problem that airflow isnot directed to the center of its airflow direction and thereby asufficient airflow speed cannot be got. If the airflow speed at thecenter of the airflow direction is insufficient, a reach distance of theairflow cannot extend and thereby there may be a case where air in aroom cannot be agitated surely.

A present embodiment provides an air circulator that can agitate air ina room surely.

An aspect of the present embodiment provides an air circulatorcomprising: a blower unit that is provided with an airflow opening on afront side of the blower unit, a grill being provided in the airflowopening; and a support unit that supports the blower unit, wherein thegrill is provided with a plurality of airflow guide blades in a spiralmanner, inner end portions of the plurality of airflow guide bladescloser to a center of the spiral of the plurality of airflow guideblades being protruded from outer end portions of the plurality ofairflow guide blades in an airflow direction, wherein the blower unithas a cover that forms an outer panel of the blower unit, and whereinthe cover has a spherical shape.

According to the present embodiment, it is possible to concentrate theairflow to the center of the airflow direction and to agitate air in aroom surely.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an air circulator according to thepresent embodiment;

FIG. 2 is a front view of the air circulator according to the presentembodiment;

FIG. 3 is a right side view of the air circulator according to thepresent embodiment;

FIG. 4 is a plan view of the air circulator according to the presentembodiment;

FIG. 5 is a back view of the air circulator according to the presentembodiment;

FIG. 6 is a cross-sectional view of the air circulator according to thepresent embodiment;

FIG. 7 is a perspective view of a blower according to a comparativeexample;

FIG. 8 is a perspective view showing a blowing state of the aircirculator according to the present embodiment;

FIG. 9A is a right side view of a grill included in a blower accordingto a practical example 1;

FIG. 9B is a right side view of a grill included in a blower accordingto a practical example 2;

FIG. 10A is a cross-sectional end face view of a featured portion of theair circulator according to the comparative example;

FIG. 10B is a cross-sectional end face view of a featured portion of theair circulator according to the practical example 1;

FIG. 11 is a graph showing test results of airflow speeds of thecomparative example and the practical examples 1 and 2;

FIG. 12 is a graph showing test results of reach distances of air of thecomparative example and the practical examples 1 and 2;

FIG. 13 is a perspective view of an air passage forming member providedin the air circulator according to the present embodiment;

FIG. 14 is a cross-sectional view of the air passage forming memberprovided in the air circulator according to the present embodiment;

FIG. 15 is a cross-sectional view of the air circulator according to thepresent embodiment;

FIG. 16 is a cross-sectional view showing an internal mechanism of theair circulator according to the present embodiment;

FIG. 17 is a perspective view showing the internal mechanism of the aircirculator according to the present embodiment;

FIG. 18 is a cross-sectional view showing the internal mechanism of theair circulator according to the present embodiment;

FIG. 19 is a perspective view showing the internal mechanism of the aircirculator according to the present embodiment;

FIG. 20 is a plan view of a control panel provided in the air circulatoraccording to the present embodiment;

FIG. 21 is a cross-sectional view of a left-right swing mechanismprovided in the air circulator according to the present embodiment;

FIG. 22 is an exploded view of a base unit provided in the aircirculator according to the present embodiment;

FIG. 23 is a cross-sectional view showing of a joint portion of the baseunit provided in the air circulator according to the present embodiment;

FIG. 24 is a graph showing an example of an adjustment pattern of avolume rate of airflow for rhythm air by the air circulator according tothe present embodiment;

FIG. 25A is a graph showing a control method of the rhythm air shown inFIG. 24 in a case where a voltage applied to a motor takes fixed values;

FIG. 25B is a graph showing a control method of the rhythm air shown inFIG. 24 in a case where a voltage applied to a motor is changedgradually;

FIG. 26A is a cross-sectional view of a grill portion included in theair circulator according to the practical example 1; and

FIG. 26B is a cross-sectional view of a grill portion included in ablower according to a modified example.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be explained indetail with reference to the drawings. Note that identical or equivalentportions to each other are labelled with identical or equivalent signsto them in the drawings. However, it should be kept in mind that thedrawings are schematic and relations between thickness and its planardimension, proportions of thicknesses of layers and so on may bedifferent from their actual ones. Therefore, specific thicknesses anddimensions should be understood in consideration of followingexplanations. In addition, of course, the drawings may include portionswhose relations and proportions of dimensions are different from theiractual ones.

[Appearance]

FIG. 1 to FIG. 5 are appearance views showing a blower 1 according tothe present embodiment, and FIG. 1 is its perspective view, FIG. 2 isits front view, FIG. 3 is its right side view, FIG. 4 is its plan viewand FIG. 5 is its back view. This blower 1 intends to improve itsairflow speed by its spherical grill structure, and is configured to beseen as being compact by its advanced spherical design.

Although it will be explained later in detail, as shown in FIG. 1 toFIG. 5, the air circulator 1 according to the present embodimentincludes a blower unit 2 that is provided with an airflow opening 11 onits front side and in which a grill 12 is provided in the airflowopening 11, and a base unit (support unit) 3 that supports the blowerunit 2, and the grill 12 is provided with plural fins 13 in a spiralmanner, and their inner end portions 13A closer to the center O of thespiral of the plural fins 13 are protruded in an airflow direction 4from their outer end portions 13B made continuous to the airflow opening11. In other words, the inner end portions 13A are protruded in theairflow direction 4 with respect to the outer end portion(s) 13B of aportion 13C of the grill 12 in which the plural fins 13 are formed. Theinner end portion(s) 13A is an inner-end side closer to the center O ofthe spiral and includes a vicinity of an inner end. The outer endportion(s) 13B is a portion of its outer-end side made continuous to theairflow opening 11. According to these, airflow is concentrated (madeconvergent) to the center, and thereby the airflow speed at the centerof the airflow direction can be improved. In addition, a reach distanceof the airflow (spiral airflow) blown out from the airflow opening 11can be extended. As the result, air in a room can be agitated surely tohomogenize a temperature in the room, and thereby it contributes toenergy savings.

Specifically, as show in FIG. 6, it is preferable that a protrusion L₁of the inner end portions 13A of the plural fins 13 with respect to theouter end portions 13B is set larger than a fin width W of the outer endportions 13B in a front-rear direction. The protrusion L₁ referred herecorresponds to a distance in the front-rear direction from a front endof the outer end portions 13B to a front end of the inner end portions13A. In addition, the fin width W is a width of the fins 13 in thefront-rear direction. Here, the fins 13 whose fin width W is constantare shown as an example, and the outer end portions 13B of the said fins13 are made continuous to the airflow opening 11. Note that the phrase“the protrusion of the inner end portions 13A of the plural fins 13 withrespect to the outer end portions 13B” can be paraphrased as “theprotrusion (of the inner end portions 13A with respect to the outer endportions 13B) of the portion 13C of the grill 12 in which the pluralfins 13 are formed”. The portion 13C in which the plural fins 13 areformed is a portion got by excluding a cap 14 on the center O of thespiral from the grill 12. According to this, the protrusion L₁ of theinner end portions 13A of the plural fins 13 with respect to the outerend portions 13B can be ensured sufficiently, and thereby an effect ofconcentrating airflow to the center can be brought surely.

In addition, it is preferable that the plural fins 13 (the portion 13Cof the grill 12 in which the plural fins 13 are formed) are graduallyprotruded in the airflow direction 4 as they are directed from the outerend portions 13B to the center O of the spiral. According to this, theeffect of concentrating the airflow to the center can be broughtefficiently and thereby the airflow speed can be improved surely.

In addition, it is preferable that the plural fins 13 (the portion 13Cof the grill 12 in which the plural fins 13 are formed) are curved so asto be convex in the airflow direction 4. According to this, the airflowspeed can be improved more efficiently by forming the grill 12 convex(spherical).

In addition, the airflow opening 11 of the blower unit 2 is formed tohave a circular shape and the protrusion L₁ of the inner end portions13A of the plural fins 13 with respect to the outer end portions 13B isset larger than 20% of a diameter of the airflow opening 11. In otherwords, the inner end portions 13A of the portion 13C of the grill 12 inwhich the plural fins 13 are formed are protruded in the airflowdirection 4 by more than 20% of the diameter of the airflow opening 11.According to this, the effect of concentrating the airflow to the centercan be brought sufficiently and thereby the airflow speed can beimproved surely.

In addition, it is preferable that the blower unit 2 has a cover 15 forforming its outer panel, and a hollow circular cylindrical airflowtunnel 16 provided inside the cover. According to this, the airflowspeed of the airflow blown out from the airflow opening 11 can be madestable. The airflow blown out from an air circulator is a spiral airflowthat flows forward while spiraling, and directionality and straightnessof the airflow are higher than those of an electric cooling fan or thelike. Such directionality and straightness of the airflow, which arespecific effects by an air circulator, can be ensured by providing theairflow tunnel 16.

In addition, it is preferable that the cover 15 of the blower unit 2 hasa front cover 15 a having the grill 12 and a rear cover 15 b capable ofbeing coupled with the front cover 15 a, and has a spherical shape inits coupled state where the front cover 15 a and the rear cover 15 b arecoupled with each other. According to this, it has a sleek sphericalshape and no sharp edge, and thereby looks compact. Further, its cuteappearance and its fashionable look can be improved.

In addition, it is preferable that each of the front cover 15 a and therear cover 15 b is formed to have a hemispherical shape so as to form aspherical shape in the coupled state, and an air passage forming member60 having the airflow tunnel 16 is provided inside the front cover 15 a,and a part of the air passage forming member 60 is protruded rearwardfrom the front cover 15 a. According to this, even in a case of having aspherical shape in their coupled state, a length of the air passageforming member 60 can be ensured.

In addition, it is preferable that the air passage forming member 60 hasthe circular hollow cylindrical airflow tunnel 16, and aradially-expanded hollow cylindrical portion that extended from a rearend of the airflow tunnel 16 and whose diameter is made gradually largeras it extends backwards. The radially-expanded hollow cylindricalportion will be explained later in detail. When the rear end of the airpassage forming member 60 is made tapered in this manner, airflow fromthe rear can be guided smoothly. Further, the airflow speed increaseswhile entering into the airflow tunnel 16 from the radially-expandedhollow cylindrical portion due to decrease of a flow passage area, andthereby it can contribute to the increase of the airflow speed.

Note that, as an example, here shown is a configuration in which acircular ring 13R intersecting with the fins 13 is provided in order toprevent fingers from being inserted through slits between the pluralfins 13, 13 and to reinforce the grill 12, but this ring 13R is notnecessarily provided.

[Details of Each Element]

Hereinafter, the air circulator 1 according to the present embodimentwill be explained further in detail by using FIG. 1 to FIG. 5.

As already explained, the cover 15 of the blower unit 2 has the frontcover 15 a and the rear cover 15 b. The front cover 15 a is ahemispherical cover made of synthetic plastic material such aspolypropylene, and the spherical grill 12 is provided in its airflowopening 11 opened at its front. The rear cover 15 b is also ahemispherical cover made of synthetic plastic material such aspolypropylene. Many air-through openings 21 for taking in external airare formed on almost an entire surface of the rear cover 15 b.

The grill 12 is a front panel formed of synthetic plastic materialhaving high impact resistance, for example. Specifically, it is formedsuch that the spiral fins 13 are made convex so as to protrude graduallyas they are directed to the center O of the spiral. When air is sentfrom behind of the grill 12 and the airflow (wind) passes through thegrill 12 in the front-rear direction, a spiral airflow that flowsforward while spiraling is generated.

The base unit 3 supports the blower unit 2 left-light swingably, andlied on a placement surface. The base unit 3 has a base lower portion 31formed to have a circular shape in its plan view, and a base upperportion 32 capable of being coupled with the base lower portion 31. Withrespect to both of the base lower portion 31 and the base upper portion32, each cover forming an outer panel can be formed of synthetic plasticmaterial such as polypropylene. A single-foot shaped support post 33 israised posteriorly from the center of the base upper portion 32, and acontrol panel 34 is disposed anteriorly from the support post 33. Here,the base unit 3 is exemplified as a support unit 3, but the support unit3 may has a structure enabling its installation on a ceiling.

[Internal Structure]

FIG. 6 is a cross-sectional view of the air circulator 1 according tothe present embodiment. As shown in this figure, the blower unit 2 is ablower device for generating airflow, and includes a fan 17 forgenerating airflow and a motor 18 for driving the fan 17. An axial-flowtype propeller fan is adopted as the fan 17 for generating the airflowin order to generate a large volume rate of the airflow. In addition, ageneral AC capacitor motor is adopted as the motor 18 for the fan 17.Note that a diameter R₀ of the fan 17 is almost 120 mm to 240 mm.

The air circulator 1 according to the present embodiment uses a motor M1for left-right swinging and a motor M2 for up-down swinging in order toperform the left-right swinging and the up-down swinging automatically.Since these two motors M1 and M2 for the swinging are required to besmall in size in order to accommodate them in the product, synchronousmotors are adopted for them. Here, the left-right swinging and theup-down swinging are automatically operated, but it is not limited tothis. For example, only the left-right swinging may be operatedautomatically.

[Convex (Spherical) Grill Structure]

Hereinafter, a spherical grill structure included in the air circulator1 according to the present embodiment will be explained in detail.Following explanations will be made while comparing a comparativeexample (flat grill structure) with practical examples 1 and 2(spherical grill structure) in order to clarify features of thespherical grill structure.

Comparative Example

FIG. 7 is a perspective view of a blower 100 according to thecomparative example. Identical or equivalent portions to those show inFIG. 1 are labelled with identical or equivalent signs to them. As showin FIG. 7, the air circulator 100 according to the comparative exampleis an air circulator provided with a flat grill structure. Namely, itincludes a blower unit 2 whose outline shape is formed to have a barrelshape, and a flat grill 12 is provided in a circular airflow opening 11opened toward its front. Similarly, this flat grill 12 also has pluralfins 13 in a spiral manner A portion of its front cover 15 a excludingthe grill 12 is formed to have a circular truncated cone shape slightlyrounded.

Practical Examples 1 and 2

FIG. 8 shows a perspective view showing a blowing state of the aircirculator 1 according to the present embodiment. As show in FIG. 8, theair circulator 1 according to the present embodiment is an aircirculator provided with a spherical grill structure. Therefore, aturning force is applied to the airflow blown forward from the grill 12so as to form a spiral convergent to the center of the airflow direction4. As the result, the airflow is made convergent to the center, andthereby the airflow speed at the center of the airflow direction 4 canbe improved. Hereinafter, a blower 1 a according to the practicalexample 1 and a blower 1 b according to the practical example 2 will befurther explained in detail as concrete examples of the air circulator 1according to the present embodiment.

FIG. 9A is a right side view of a portion of the grill 12 included inthe air circulator 1 a according to the practical example 1, and FIG. 9Bis a right side view of a portion of the grill 12 included in the aircirculator 1 b according to the practical example 2. As shown in FIG.9A, in the air circulator 1 a according to the practical example 1, acurvature radius R of the grill 12 is about 105 mm in a case where adiameter R₀ of the fan 17 is about 150 mm, for example. On the otherhand, as shown in FIG. 9B, in the air circulator 1 b according to thepractical example 2, a curvature radius R of the grill 12 is about 92mm, for example. Fundamental structures of the air circulators 1 a and 1b according to the practical example 1 and 2 are identical to each otherwith the exception that the curvature radii of their grills 12 aredifferent from each other. For example, both of the air circulator 1 aaccording to the practical example 1 and the air circulator 1 baccording to the practical example 2 have an identical feature in whichthe front ends of the inner end portions 13A is protruded with respectto the front ends of the outer end portions 13B.

Next, operational differences among the comparative example and thepractical examples 1 and 2 will be explained. FIG. 10A is across-sectional end face view of a featured portion of the aircirculator 100 according to the comparative example, and FIG. 10B is across-sectional end face view of a featured portion of the aircirculator 1 a according to the practical example 1. Arrows in thedrawings show the airflow blown out from the airflow openings 11. Asshown in FIG. 10A, by the air circulator 100 according to thecomparative example, the plural spiral fins 13 are arranged on thesingle flat plane, so that the airflow is hardly made convergent to thecenter of the airflow direction 4. On the other hand, as shown in FIG.10B, by the air circulator 1 a according to the practical example 1, theplural spiral fins 13 are arranged three-dimensionally, so that theairflow is readily made convergent to the center of the airflowdirection 4. Although the air circulator 1 a according to the practicalexample 1 is explained here, the same feature that the airflow isreadily made convergent to the center of the airflow direction 4 can bebrought also by the air circulator 1 b according to the practicalexample 2. Note that the phrase “the center of the airflow direction 4”can be rephrased as “in front of the center of the airflow opening 11”or “on an extended line of a straight line that is parallel to therotational axis of the fan 17 and passes through the center O of thespiral”.

(Comparison of Airflow Speeds)

FIG. 11 is a graph showing test results of the airflow speeds of thecomparative example and the practical examples 1 and 2. Its verticalaxis indicates an airflow speed [m/s] and its horizontal axis indicatesa distance in a left-right direction with the center of the airflowdirection 4 defined as a reference position “0”. Specifically, signs P⁻⁴to P₄ shown along the horizontal axis correspond to positions of signsP⁻⁴ to P₄ show in FIG. 10B, respectively. As show in FIG. 11, in thecomparative example and the practical examples land 2, the airflowspeeds get lower as the distance in the right-left direction getslarger. However, a portion near the center of the airflow direction 4 ina waveform of the comparative example is flat, whereas a portion nearthe center of the airflow direction 4 in each waveform of the practicalexamples 1 and 2 is protuberant. Namely, the airflow speeds in an areanear the center of the airflow direction 4 in the practical samples 1and 2 are higher than that in the comparative example.

According to the practical examples 1 and 2, it can be known that theairflow is made convergent to the center of the airflow direction 4 bymaking the grill 12 spherical and thereby the airflow speed can beimproved. It is also know by the comparison between the practicalexample 1 (the curvature radius R105) and the practical example 2 (thecurvature radius R92) that the airflow is made further convergent to thecenter of the airflow direction 4 in the practical example 2 and therebythe airflow speed becomes slightly higher.

Note that it is preferable that the curvature radius R of the grill 12is about 80 mm to about 120 mm (more preferably, about 90 mm to about110 mm) in the case where the diameter R₀ of the fan 17 is about 150 mm,for example. Although explanations made here are premised on the casewhere the diameter R₀ of the fan 17 is about 150 mm, the diameter R₀ ofthe fan 17 can be changed arbitrarily within a range about 120 mm toabout 240 mm, for example. Needless to say, if the diameter R₀ of thefan 17 changes, the preferable range (about 80 mm to about 120 mm) ofthe curvature radius R of the grill 12 may change similarly.

(Comparison of Reach Distances of Airflows)

FIG. 12 is a graph showing test results of reach distances of theairflows of the comparative example and the practical examples 1 and 2.As shown in FIG. 12, the reach distance [m] of the comparative exampleis about 28 m, but that of the practical example 1 is about 30 m andthat of the practical example 2 is about 29 m. In this manner, it isknow that, according to the practical examples 1 and 2, the airflow ismade convergent to the center of the airflow direction 4 by forming thegrill 12 spherical and thereby the reach distance of the airflow can beimproved. Although a strong airflow that flows farther can be broughtdue to its spiral airflow also in the comparative example, the reachdistances can be extended further and according to the practicalexamples 1 and 2 thereby an air agitation effect inherently brought byan air circulator becomes prominent.

(Correlation of Fan and Grill)

As shown in FIG. 6, it is denoted that the curvature radius of the grill12 is R, the diameter of the fan 17 is R₀, an outer diameter of theblower unit 2 is R₁, and a diameter of the airflow opening 11 (an innerdiameter of the airflow tunnel 16) is R₂. It is acceptable that thediameter of the hollow cylindrical airflow tunnel 16 may get slightlylarge or small.

First, the preferable range of the curvature radius R of the grill 12 isabout 80 mm to about 120 mm (more preferably, about 90 mm to about 110mm) in the case where the diameter R₀ of the fan 17 is about 150 mm, andits actually measured value is about 105 mm. In view of relation betweenthe diameter R₀ of the fan 17 and the curvature radius R of the grill12, it can be understood that the preferable range of the curvatureradius R of the grill 12 is a range in which R/R₀=about 53.3% to about80.0% (more preferably, about 60.0% to about 73.3%) is satisfied.

If the curvature radius R of the grill 12 is smaller than its lowerlimit value, the grill 12 in the blower unit 2 has a distorted shape.The lower limit value referred to here is about 53.3% (more preferably,about 60.0%) of the diameter R₀ of the fan 17. On the other hand, if thecurvature radius R of the grill 12 is larger than its upper limit value,the effect of the increase of the airflow speed cannot be broughtsufficiently. The upper limit value referred to here is about 80.0%(more preferably, about 73.3%) of the diameter R₀ of the fan 17.

In addition, a preferable range of the outer diameter R₁ of the blowerunit 2 is about 160 mm to about 240 mm in the case where the diameter R₀of the fan 17 is about 150 mm. In view of relation between the outerdiameter R₁ of the blower unit 2 and the diameter R₀ of the fan 17, itcan be understood that the preferable range of the outer diameter R₁ ofthe blower unit 2 is a range in which R₁/R₀=about 107% to about 160% issatisfied. Since the blower unit 2 has a spherical shape, the outerdiameter R₁ of the blower unit 2 is about twice as large as thecurvature radius R of the grill 12.

If the outer diameter R₁ of the blower unit 2 is smaller than about 107%of the diameter R₀ of the fan 17, a clearance between the fan 17 and theairflow tunnel 16 cannot be ensured and thereby contacts of the fan 17with the inner face of the airflow tunnel 16 are concerned, andproduction becomes difficult. On the other hand, if the outer diameterR₁ of the blower unit 2 is larger than about 160% of the diameter R₀ ofthe fan 17, a size of the blower unit 2 becomes too large and thereby itbecomes top-heavy to dispute a balance with the base unit 3.

In addition, a preferable range of the diameter R₂ of the airflowopening 11 is about 155 mm to about 175 mm in the case where thediameter R₀ of the fan 17 is about 150 mm. In view of relation betweenthe diameter R₂ of the airflow opening 11 and the diameter R₀ of the fan17, it can be understood that the preferable range of the diameter R₂ ofthe airflow opening 11 is a range in which R₂/R₀=about 103% to about117% is satisfied. When making the diameter R₂ of the airflow opening 11small, an advantage of ensuring a length of the airflow tunnel 16 can bebrought.

If the diameter R₂ of the airflow opening 11 is smaller than about 103%of the diameter R₀ of the fan 17, a clearance between the fan 17 and theairflow tunnel 16 cannot be ensured and thereby their contacts areconcerned, and production becomes difficult. On the other hand, if thediameter R₂ of the airflow opening 11 is larger than about 117% of thediameter R₀ of the fan 17, a length of the airflow tunnel 16 cannot beensured in the spherical blower unit 2 and thereby it becomes difficultto keep the directionality and the straightness of the blown-outairflow.

In view of relation between the diameter R₂ of the airflow opening 11and the outer diameter R₁ of the blower unit 2, it can be understoodthat the preferable range of the diameter R₂ of the airflow opening 11is a range in which R₂/R₁=about 74% to about 83% is satisfied. When theratio R₂/R₁ is relatively small in this manner, brought is an effectthat an area occupied by the airflow opening 11 in a front view of theblower unit 2 looks small.

If the diameter R₂ of the airflow opening 11 is smaller than about 74%of the outer diameter R₁ of the blower unit 2, a clearance between thefan 17 and the airflow tunnel 16 cannot be ensured and thereby theircontacts are concerned further. On the other hand, if the diameter R₂ ofthe airflow opening 11 is larger than about 83% of the outer diameter R₁of the blower unit 2, a length of the airflow tunnel 16 cannot beensured in the spherical blower unit 2 and thereby it becomes moredifficult to keep the directionality and the straightness of theblown-out airflow.

[Spherical Design+Inside Airflow Tunnel]

The blower unit 2 has a sleek spherical shape and no sharp edge, andthereby looks compact. In addition, its cute appearance and itsfashionable look can be improved. On the other hand, the airflow tunnel16 necessarily has a sufficient length in order to stabilize the airflowspeed of the airflow blown out from the air circulator 1. Therefore, afollowing configuration is adopted in the air circulator 1 according tothe present embodiment.

FIG. 13 is a perspective view of the air passage forming member 60included in the air circulator 1 according to the present embodiment. Asshown in FIG. 13, the air passage forming member 60 is a member forforming an air passage, and has the grill 12, the airflow tunnel 16 andthe radially-expanded hollow cylindrical portion 19. The air passageforming member 60 is made of synthetic plastic material by integrallymolding the grill 12, the airflow tunnel 16 and the radially-expandedhollow cylindrical portion 19.

The airflow tunnel 16 is a hollow cylindrical member provided onradially outer side of the fan 17, and the inner diameter of the airflowtunnel 16 is almost identical to the inner diameter of the airflowopening 11.

The radially-expanded hollow cylindrical portion 19 is a portion forcoupling with the rear cover 15 b, and is a hollow cylindrical taperedmember whose diameter is made gradually larger as it extends backwards.Plural engagement pawls 19 b that are to be engaged with the rear cover15 b are provided on a rearmost end 19 a of the radially-expanded hollowcylindrical portion 19.

Plural reinforcing ribs 19 c are raised vertically from an outercircumferential surface of the airflow tunnel 16 and theradially-expanded hollow cylindrical portion 19, and thereby strength ofthe radially-expanded hollow cylindrical portion 19 is ensured. Eachouter edge of the reinforcing ribs 19 c is formed so as to contact withan inside surface of an outer-shell spherical cover member 15C.

When attaching the outer-shell spherical cover member 15C to the outersurface of the air passage forming member 60, the front face of thegrill 12 (the front end faces of the plural fins 13) and the outercircumferential face of the outer-shell spherical cover member 15Cconstitute a continuous spherical surface.

It becomes possible, by integrally molding the airflow tunnel 16 and thegrill 12, to reduce component counts and production costs while ensuringstrength of a joint portion between the airflow tunnel 16 and the grill12.

In addition, by forming the continuous spherical surface with the frontface of the grill 12 (the front end faces of the plural fins 13) and theouter circumferential face of the outer-shell spherical cover member15C, no stepped surface is formed at a portion between the grill 12 andthe outer-shell spherical cover member 15C in the blower unit 2 andthereby a beautiful spherical shape can be brought to improve theappearance.

By providing the airflow tunnel 16 inside the outer-shell sphericalcover member 15C, the directionality and the straightness of theblown-out airflow can be improved and performance as an air circulatorcan be made stable.

(Air Passage Forming Member)

FIG. 14 is a cross-sectional view of the air passage forming member 60included in the air circulator 1 according to the present embodiment. Asshown in this figure, it is denoted that an entire length of the airpassage forming member 60 is L₀, the protrusion of the grill 12 is L₁, alength of the airflow tunnel 16 is L₂, a length of the radially-expandedhollow cylindrical portion 19 is L₃, the curvature of the grill 12 is R,and a tapered angle of an inner circumferential surface of theradially-expanded hollow cylindrical portion 19 is θ. The entire lengthL₀ of the air passage forming member 60 is a length from the front endof the grill 12 to the rear end of the radially-expanded hollowcylindrical portion 19, and L₀=L₁+L₂+L₃. Explanations made hereinafterare also premised on the case where the diameter R₀ of the fan 17 isabout 150 mm Needless to say, if the diameter R₀ of the fan 17 changes,their dimensions may change similarly.

A preferable range of the length L₂ of the airflow tunnel 16 is about 45mm to about 60 mm in the case where the diameter R₀ of the fan 17 isabout 150 mm, and its actually measured value is about 50 mm. It can beunderstood that the preferable range of the length L₂ of the airflowtunnel 16 is about 30% to about 40% of the diameter R₀ of the fan 17(about 150 mm). When the airflow tunnel 16 is made long, thedirectionality and the straightness of the airflow can be ensured.

If the length L₂ of the airflow tunnel 16 is smaller than about 30% ofthe diameter R₀ of the fan 17 (about 45 mm), the airflow tunnel 16 istoo short and thereby the directionality and the straightness of theairflow cannot be ensured. On the other hand, if the length L₂ of theairflow tunnel 16 is larger than about 40% of the diameter R₀ of the fan17 (about 60 mm), the protrusion L₁ of the grill 12 or the length L₃ ofthe radially-expanded hollow cylindrical portion 19 becomes small andthereby the effect of the increase of the airflow speed cannot bebrought sufficiently.

In addition, the entire length L₀ of the air passage forming member 60is set larger than the curvature radius R of the grill 12 (105 mm).Therefore, the rear end portion (the radially-expanded hollowcylindrical portion 19) of the air passage forming member 60 protrudesrearward from the hemispherical front cover 15 a, and the rear endportion of the air passage forming member 60 is installed into the rearcover 15 b. It becomes easier to ensure the length L₂ of the airflowtunnel 16 as the entire length L₀ of the air passage forming member 60gets larger, but the grill 12 is formed spherically and thereby thelength L₂ cannot be made larger by extending the airflow tunnel 16forward. In the present embodiment, the length L₂ of the airflow tunnel16 is ensured by setting the entire length L₀ of the air passage formingmember 60 larger than the curvature radius R of the grill 12 andinstalling a part of the radially-expanded hollow cylindrical portion 19on a rear side of the airflow tunnel 16 into the rear cover 15 b.Further, the length L₃ of the radially-expanded hollow cylindricalportion 19 can be also ensured sufficiently.

In addition, the tapered angle θ of the radially-expanded hollowcylindrical portion 19 is set to 15 degrees to 30 degrees. By making theradially-expanded hollow cylindrical portion 19 at the rear end of theair passage forming member 60 tapered with the angle 15 degrees to 30degrees in this manner, the airflow from the rear can be guidedsmoothly. Further, the airflow speed increases while entering into theairflow tunnel 16 from the radially-expanded hollow cylindrical portion19 due to the decrease of the flow passage area, and thereby it cancontribute to the increase of the airflow speed.

If the tapered angle θ of the radially-expanded hollow cylindricalportion 19 is smaller than 15 degrees, it becomes difficult to get theeffect of the increase of the airflow speed due to the decrease of theflow passage area while entering into the airflow tunnel 16 from theradially-expanded hollow cylindrical portion 19. On the other hand, ifthe tapered angle θ is larger than 30 degrees, airflow resistance in theradially-expanded hollow cylindrical portion 19 becomes large andthereby it is concerned that the airflow from the rear cannot flowsmoothly.

(Relation Between Fan and Air Passage Forming Member)

A flow passage(s) of air 61 flowing in the air circulator 1 is shown inFIG. 15. The airflow speed of the air 61 flowing in the air circulator 1increases while entering into the airflow tunnel 16 from theradially-expanded hollow cylindrical portion 19 due to the decrease ofthe flow passage area. Therefore, it contributes to the increase of theairflow speed of the airflow blown out air from the airflow opening 11.Note that, as shown in FIG. 15, the air passage forming member 60surrounds the fan 17 from the outside and the air passage forming member60 extends backward from the position of the rear end of the fan 17.

[Wiring of Electrical Cables]

FIG. 16 and FIG. 17 show an internal mechanism of the air circulator 1according to the present embodiment. Specifically, FIG. 16 is across-sectional view in a case of cross-sectioning on a left side fromthe center of the blower unit 2, and FIG. 17 is a perspective view in acase of being viewed downward from obliquely rear left with the cover 15and the air passage forming member 60 removed.

As shown in FIG. 16 and FIG. 17, a motor cover 71 is held from its bothsides by support pillars 70 raised up from the base unit 3, and theblower unit 2 swings with respect to the base unit 3 about this heldposition as an axial shaft 72 of the up-down swinging. Here, anelectrical cable 73 connected to the motor 18 (see FIG. 6) for the fan17 accommodated in the motor case 71 and to the motor M2 (see FIG. 6)for the up-down swinging may be drawn out through the axial shaft 72.The electrical cable 73 drawn out through the axial shaft 72 of theup-down swinging is drawn into the inside of the based unit 3 through ahole 36 formed on an upper face 35 of the base unit 3. The electricalcable 73 may be fixed at an arbitrary position of the support pillar 70.According to the configuration of passing the electrical cable 73through the rotational center of the up-down swinging in this manner, notwisting force is applied to the electrical cable 73 during the up-downswinging and thereby the electrical cable 73 can be prevented frombreaking.

[Up-Down Swing Mechanism]

FIG. 18 and FIG. 19 show the internal mechanism of the air circulator 1according to the present embodiment. Specifically, FIG. 18 is across-sectional view in a case of cross-sectioning on a right side fromthe center of the blower unit 2, and FIG. 19 is a perspective view in acase of being viewed downward from obliquely rear right with the cover15 and the air passage forming member 60 removed.

In addition, as shown in FIG. 18 and FIG. 19, an output shaft 94 of themotor M2 for the up-down swinging is linked with the support pillar 70via a link mechanism 90 for the up-down swinging. Specifically, the linkmechanism 90 includes a swing arm member 91 fixed with the output shaft94 of the motor M2 for the up-down swinging, a fixed member 93 fixed onthe support pillar 70, and a bow-shaped link member 92 whose one end ispivotally coupled with the swing arm member 91 and whose another end ispivotally coupled with the fixed member 93. A rubber washer 95 may beinterposed between the swing arm member 91 and the link member 92, and arubber washer 96 may be interposed between the link member 92 and thefixed member 93. According to this, vibrations are absorbed by therubber washers 95 and 96, and thereby backlashes of the synchronousmotor (the motor 2 for the up-down swinging) and noise of the linkmechanism 90 due to clearances between the members 91, 92 and 93 can beprevented. Note that one of the two rubber washer 95 and 96 can beomitted.

[Control Panel]

FIG. 20 is a plan view of the control panel 34 included in the aircirculator 1 according to the present embodiment. As shown in FIG. 20, apower button 34 a, a timed power-off button 34 b, an airflow volumebutton 34 c, a rhythm button 34 d, a swing button 34 e and so on areincluded in the control panel 34. The power button 34 a is a button forsetting power off/on. The timed power-off button 34 b is a button forsetting a power-off timer. The airflow volume button 34 c is a buttonfor adjusting a volume rate of airflow of the blower unit 2, and alower/higher setting of its volume rate of airflow can be changed infive levels sequentially, breeze, low, middle, high and turbo, every onepushing. The rhythm button 34 e is a button for setting anafter-explained rhythm air. The sing button 34 d is a button for settingturning-on/off of the up-down swinging and the left-right swinging.

[Rear Cover]

Next, the rear cover 15 b will be explained further in detail withreference to FIG. 5. As already explained, the large number of theair-through openings 21 for taking in external air are formed on almostthe entire of the rear cover 15 b. In the present embodiment, air holes21 a are additionally formed on a portion of the rear cover 15 b behindthe motor. Therefore, external air is taken in from the air holes 21 abehind the motor while the motor 18 drives the fan 17, so that not onlylarger volume rate of airflow can be ensured but also airflow generatedby the motor 18 itself brings a cooling effect for heat generationmeasures.

[Left-Right Swing Mechanism]

FIG. 21 is a cross-sectional view showing a left-right swing mechanism43 included in the air circulator 1 according to the present embodiment.As shown in FIG. 21, a void space is provided in the base unit 3, andthe left-right swing mechanism 43 is accommodated in the void space. Theleft-right swing mechanism 43 includes a fixed plate 41 fixed with thebase upper portion 32, a center shaft 42 made integrated with the fixedplate 41 by insert-molding, and the motor M1 for the swinging that isfixed on an upper surface of the fixed plate 41. It includes a shaftreceiving member (bush) 44 that is made of plastics and into which alower end of the center shaft 42 is inserted, and an engagement pawl 44a is integrally formed along a lower-end inner circumference of theshaft receiving member 44. A notched groove 42 a is formed along alower-end outer circumference of the center shaft 42, the engagementpawl 44 a is pressed into the notched groove 42 a.

FIG. 22 is an exploded view of the base unit 3 included in the aircirculator 1 according to the present embodiment. Hereinafter, theleft-right swing mechanism 43 will be explained further in detail byusing FIG. 22.

As already explained, the void space is provided in the base unit 3, andthe left-right swing mechanism 43 is accommodated in the void space. Theleft-right swing mechanism 43 includes the fixed plate 41, the motor M1(see FIG. 21) for the swinging that is fixed on the upper surface of thefixed plate 41, an eccentric cam 43A fixed with an output shaft 43E ofthe swinging motor M1, a fixed shaft 43D fixed with the base lowerportion 31, and a bow-shaped coupling link 43B whose one end ispivotally coupled with the eccentric cam 43A and whose another end ispivotally coupled with the fixed shaft 43D.

In addition, the fixed plate 41 is fixed with the base upper portion 32,and the center shaft 42 is swivelably inserted into the shaft receivingmember 44. The motor M1 for the swinging (including the eccentric cam43A fixed with its output shaft 43E) and the fixed shaft 43D areprovided at a position distanced from the center shaft 42.

In addition, the hollow cylindrical shaft receiving member 44, on theinner circumference of whose lower end the engagement pawl 44 a isformed, is inserted into a shaft insertion hole 47 formed on the baselower portion 31. The center shaft 42 is inserted into this shaftreceiving member 44. The notched groove 42 a is formed on the outercircumference of the lower end of the center shaft 42, and theengagement pawl 44 a that serves as an engagement flange is pressed intothe said notched groove 42 a. A cord folder 45 is installed beneath theshaft receiving member 44, and then an opening 31 b formed on a lowerplate of the base lower portion 31 is closed by a bottom cap 46.

In addition, the fixed plate 41 and an upper end of the center shaft 42are insert-molded with each other, and the base upper portion 31 and thebase lower portion 32 are coupled with each other by the center shaft 42and the shaft receiving member 44 for the center shaft 42 is fixed withthe base lower portion 31. Since the center shaft 42 is inserted intothe shaft insertion hole 47 with the shaft receiving member 44interposed therebetween, no clearance is formed between the center shaft42 and the shaft insertion hole 47 to prevent frictions with the shaftinsertion hole 47 due to swinging of the center shaft 42 and noisesgenerated by them and to smoothen the swinging of the base upper portion32 (the blower unit 2) about the center shaft 42.

When a user turns on the left-right swinging by pressing down the swingbutton 34 e on the control panel 34, the eccentric cam 43A fixed withthe output shaft 43E of the motor M1 for the swinging rotateseccentrically, and the one end of the coupling link 43B pivotallycoupled with the eccentric cam 43A moves in a circular motion. Since theother end of the coupling link 43B is pivotally coupled with the fixedshaft 43D fixed with the base lower portion 31, the base upper portion32 and the blower unit 2 attached thereon swivel (swing) about thecenter shaft 42 in the left-right direction due to the said circularmotion according to a radius distance of the circular motion.

As explained above, the air circulator 1 according to the presentembodiment is the air circulator 1 in which the base lower portion 31and the base upper portion 32 that is provided swingably on the baselower portion 31 are coupled with each other with the center shaft 42passed through them and the blower unit 2 is provided on the base upperunit 32; the shaft receiving member 44 is inserted into the base lowerportion 31; the center shaft 42 is swivelably inserted into the saidshaft receiving member 44; and the fixed plate 41 provided in the baseupper portion 32 and the upper end of the center shaft 42 areinsert-molded with each other. Therefore, it becomes possible to reducecomponent counts and production costs while ensuring strength of thejoint portion thereof.

In addition, the fixed plate 41 provided in the base upper portion 32 ismade of plastics. Therefore, the electrical wire(s) can be preventedfrom being damaged when the electrical wire contacts with edges(corners) of the fixed plate 41.

In addition, the engagement pawl 44 a is integrally molded of plasticson the inner circumference of the lower end of the shaft receivingmember 44 for the center shaft 42. Therefore, the engagement pawl 44 afunctions an alternative of an E-ring, so that it is not needed to usean E-ring and thereby it becomes possible to reduce component counts andproduction costs.

[Joint Portion of Base Unit]

FIG. 23 is a cross-sectional view showing a joint portion of the baseunit 3 included in the air circulator 1 according to the presentembodiment. As shown in FIG. 23, an annular inner wall 31 a is raised onan inner side of a circumferential edge of the base lower portion 31,and a circumferential edge of the base upper unit 32 covers over theannular inner wall 31 a of the base lower portion 31. Therefore, a gapbetween the base upper portion 32 and the base lower portion 31 isconcealed and thereby made unemphatic by the annular inner wall 31 a.Further, a margin can be ensured for a clearance between the upper andlower ones, it becomes possible to prevent the base upper portion 32 andthe base lower portion 31 from scratching each other during theleft-right swinging and to restrict noises generated due to thescratching. Furthermore, it becomes possible to restrict dusts or thelike from entering into the inside of the base unit 3 through the gapbetween the base upper portion 32 and the base lower portion 31.

[Control of Rhythm Air]

The air circulator 1 according to the present embodiment includes acontroller 50 for controlling powering on/off of the power source,operations of the power-off timer, rotational speed of the motor 18, theswinging and so on. The controller 50 is a control board configured of aCPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (RandomAccess Memory) and so on (see FIG. 6). When a user turns on the rhythmmode by pressing down the rhythm button 34 d on the control panel 34,the controller 50 achieves the rhythm air by controlling the rotationalspeed of the motor 18.

FIG. 24 is a graph showing an example of an adjustment pattern of avolume rate of the airflow for the rhythm air blown out from the aircirculator 1 according to the present embodiment. Its horizontal axisindicates time and its vertical axis indicates an intensity setting ofthe volume rate of the airflow. As shown in FIG. 24, in the rhythm mode,weak wind and strong wind are switched over so as not to be simplerepeats to generate a fluctuation effect and so as to be similar tonatural winds.

Specifically, in the rhythm mode, following twenty airflow volume ratecontrol processes (1) to (20) are executed repeatedly. Namely, when theairflow volume rate control processes (1) to (20) are sequentially done,the process flow returns back to the airflow volume rate control process(1). For example, the airflow volume rate control process (1) means thatan operational time with a volume rate of airflow F2 is set to 15seconds. It may be adopted that a volume rate of airflow F1 correspondsto a volume rate of airflow “breeze”, a volume rate of airflow F2corresponds to a volume rate of airflow “low” and a volume rate ofairflow F3 corresponds to a volume rate of airflow “middle”.

(1) volume rate of airflow F2 for 15 seconds→(2) volume rate of airflowF1 for 15 seconds→(3) volume rate of airflow F2 for 15 seconds→(4)volume rate of airflow F1 for 15 seconds→(5) volume rate of airflow F3for 30 seconds→(6) volume rate of airflow F1 for 30 seconds→(7) volumerate of airflow F2 for 15 seconds→(8) volume rate of airflow F1 for 15seconds→(9) volume rate of airflow F3 for 30 seconds→(10) volume rate ofairflow F1 for 30 seconds→(11) volume rate of airflow F2 for 15seconds→(12) volume rate of airflow F1 for 15 seconds→(13) volume rateof airflow F2 for 15 seconds→(14) volume rate of airflow F1 for 15seconds→(15) volume rate of airflow F3 for 30 seconds→(16) volume rateof airflow F1 for 30 seconds→(17) volume rate of airflow F2 for 15seconds→(18) volume rate of airflow F1 for 15 seconds→(19) volume rateof airflow F2 for 15 seconds→(20) volume rate of airflow F1 for 15seconds . . . .

Note that the twenty airflow volume rate control processes (1) to (20)are set as a single unit of the repeats here, but the number of airflowvolume rate control processes configuring such a single unit is notlimited. In addition, the case where the three settings of the volumerate of airflow F1, F2 and F3 are used for the rhythm air is shown as anexample, but the number of the airflow volume rate settings and theintensity of the airflow volume rate setting(s) used for the rhythm airare not also limited. Further, the case where a single unit of theairflow volume rate control process is set to 15 seconds or 30 secondsis shown as an example, but it can be done arbitrarily to increase ordecrease the number of seconds for this single unit.

FIG. 25 are graphs showing control methods of the rhythm air shown inFIG. 24. Its horizontal axis indicates time and its vertical axisindicates a voltage applied to the motor 18. As shown in FIG. 25A, thevoltage applied to the motor 18 may be kept at a constant value (V2, V2,V3, . . . ) during a unit time duration (t1-t2, t2-t3, t3-t4, . . . ).Alternatively, as shown in FIG. 25B, the voltage applied to the motor 18may be changed gradually to change the rotational speed of the motor 18moderately at the transition between the airflow volume rate settings.By changing the voltage applied to the motor 18 gradually, a torqueapplied to the fan 17 increases gradually and thereby a load applied tothe motor 18 due to air resistance of the fan 17 can be decreased. Inaddition, by changing the rotational speed of the motor 18, i.e. therotational speed of the fan 17, gradually, the transition of the airflowvolume rate settings can be done smoothly and thereby it can be madesimilar to natural winds and sounds of the fan 17 at the transition ofthe airflow volume rate settings can be reduced.

As explained above, the controller 50 executes the control for repeatingthe rhythm air volume rate adjustment pattern including plural airflowvolume rate settings with (irregular) combinations of the plural typesof airflow volume intensities and unit seconds, so that the fluctuationeffect can be generated and it can be made similar to natural winds byswitching over weak wind and strong wind so as not to be simple repeatsin the rhythm mode.

In addition, the controller 50 increase or decrease the voltage value ofthe motor 18 for driving the fan 17 gradually when controlling therhythm air. Therefore, the transition of the airflow volume ratesettings can be done moderately and thereby it can be made similar tonatural winds and sounds of the fan 17 at the transition of the airflowvolume rate settings can be reduced.

Modified Example

FIG. 26A is a cross-sectional view of the air passage forming member 60included in the air circulator 1 a according to the practical example 1,and FIG. 26B is a cross-sectional view of an air passage forming member60 c included in a blower according to a modified example. As shown inFIG. 26A, in the practical example 1, the fin widths W of the fins 13 inthe front-rear direction are almost identical at any portion. On theother hand, as shown in FIG. 26B, in the modified example, the finwidths W of the fins 13 in the front-rear direction are differentiatedsuch that the fin widths W gradually increases as transitioning from theouter end portions 13B to the inner end portions 13A in the fins 13 andthe positions of the rear ends of all the fins 13 are located at aposition of the airflow opening 11. Namely, when viewing the grill 12from its rear side, height positions of all the fins 13 are made flat.Also according to this modified example, it can be expected similarly tothe practical examples 1 and 2 that the airflow tends to be concentratedto the center of the airflow direction 4.

Other than the above example, various modification may be made in thegrill 12. Namely, it is necessary that the grill 12 is provided with theplural spiral fins 13 and the inner end portions 13A closer to thecenter O of the spiral of the plural fins 13 are protruded in theairflow direction 4 from the outer end portions 13B made continuous tothe airflow opening 11. The grill 12 that satisfies the above conditionis included in the present embodiment. For example, the grill 12 maytake various shape, when being viewed from its side, other than theconvex shape, such as a shape including two protrusions, a truncatedcone shape, a shape only whose center is concave, a stepped shape, ashape similar to a mosque of Islamic temple, a shape like Mt. Fuji.

Other Embodiments

Some embodiments are explained as described above, the descriptions andthe drawings that are part of the disclosures are examples, and youshould not think that they provide limitations. Based on thesedisclosures, various alternative embodiments, practical examples andoperational technologies may be made known for person skilled in theart.

What is claimed is:
 1. An air circulator comprising: a blower unit thatis provided with an airflow opening on a front side of the blower unit,a grill being provided in the airflow opening; and a support unit thatsupports the blower unit, wherein the grill is provided with a pluralityof airflow guide blades in a spiral manner, inner end portions of theplurality of airflow guide blades closer to a center of the spiral ofthe plurality of airflow guide blades being protruded from outer endportions of the plurality of airflow guide blades in an airflowdirection, wherein the blower unit has a cover that forms an outer panelof the blower unit, and wherein the cover has a spherical shape.
 2. Theair circulator according to claim 1, wherein the cover has a front coverhaving the grill and a rear cover capable of being coupled with thefront cover, and wherein each of the front cover and the rear cover hasa hemispherical shape so as to form the spherical shape when the frontcover and the rear cover are coupled with each other.
 3. The aircirculator according to claim 1, wherein the cover has a front coverhaving the grill and a rear cover; wherein the blower unit is providedwith a hollow circular cylindrical airflow tunnel formed inside thecover, wherein an air passage forming member forming the airflow tunnelis provided inside the front cover, and wherein a part of the airpassage forming member is protruded rearward from the front cover. 4.The air circulator according to claim 3, wherein the airflow tunnel isformed inside the air passage forming member, and wherein the airpassage forming member is provided with a radially-expanded hollowcylindrical portion that extends from a rear end of the airflow tunneland whose diameter is made gradually larger as extending backwards. 5.The air circulator according to claim 1, wherein the airflow opening isformed to have a circular shape, and wherein a protrusion of the innerend portions of the plurality of airflow guide blades with respect tothe outer end portions is set larger than 20% of a diameter of theairflow opening.
 6. The air circulator according to claim 1, wherein aprotrusion of the inner end portions of the plurality of airflow guideblades with respect to the outer end portions is set larger than a widthof the outer end portions of the airflow guide blades in a front-reardirection.
 7. The air circulator according to claim 1, wherein theplurality of airflow guide blades is gradually protruded in the airflowdirection as being directed from the outer end portions to the center ofthe spiral.
 8. The air circulator according to claim 7, wherein theplurality of airflow guide blades is curved so as to be convex in theairflow direction.